Coating process

ABSTRACT

A METHOD OF COATING A SHEET OF MATERIAL WITH A TACKY SUBSTANCE INVOLVING CAUSING THE COATED SHEET OF MATERIAL TO PASS OVER AN ABSORBENT SURFACE WHICH HAS ABSORBED FLUID AND WHICH CHANGES THE DIRECTION OF TRAVEL OF SAID MATERIAL AND APPLYING THE FLUID TO THE ABSORBENT SURFACE DURING THE COATING PROCESS TO PREVENT STICKING OF THE COATED MATERIAL TO THE COATING MACHINERY. APPARATUS FOR CARRYING OUT SAID METHOD.

1, 1972 A. R. RIZZO COATING PROCESS Original Filed Sept. 20, 1966 oumqaw I Arro fz United States Patent-615cc 3,681,121 Patented Aug. 1, 1972 3,681,121 COATING PROCESS Anthony R. Rizzo, Lynn, Mass., assignor to AFCO Products, Inc., Somerville, Mass. Continuation of application Ser. No. 580,656, Sept. 20, 1966. This application Aug. 21, 1970, Ser. No. 66,104

Int. Cl. B44d 1/44 US. Cl. 117-119.4 8 Claims ABSTRACT OF THE DISCLOSURE A method of coating a sheet of material with a tacky substance involving causing the coated sheet of material to pass over an absorbent surface which has absorbed fluid and which changes the direction of travel of said material and applying the fluid to the absorbent surface during the coating process to prevent sticking of the coated material to the coating machinery. Apparatus for carrying out said method.

This is a continuation of application Ser. No. 580,656, filed Sept. 20, 1966 and now abandoned.

This invention relates to a coating process and more particularly to a process for coating a continuous web material with a tacky substance.

This invention relates to a coating and more particularly to a process for coating a continuous web material with a tacky substance.

In the conventional process for making materials which are coated with a sticky or tacky substance, such as flashing, waterproofing and roofing materials, a continuous web material is passed through a dip-tank of the coating substance, which is preferably (but not limited to) an asphalt or bituminous compound. The amount of coating on both sides of the web is controlled by the heat of the coating substance in conjunction with various mechanical means to smooth the coating. After leaving the dip-tank the coating substance on the web material is in a heated and sticky or tacky state. The web must then be cooled and the coating set so that it may be wound on a takeup roll without the layers sticking together.

One conventional method to accomplish this cooling and setting is to drive the coated web vertically by means of a driven roll system at an upper position, preferably past cooling fans, over the driven roll system (at which point the web reverses direction) and to return the coated web to the lower position where it is finally wound on a suitable take-up roll after passing over a series of ground level rolls. This vertical movement provides a maximum amount of space within which the coating may be cooled with a minimum of floor space being used. The vertical length of travel is limited, however, because the weight of the coated web often causes tension problems, which in turn create tearing and web breaking since the web is supported at its upper position by the aforementioned driver roll system. This limits the amount of cooling of the coated web. If the coating on the web is not sufficiently set and cooled, it will stick to the driven roll system at the top of the vertical run. If the coating is still hot and tacky when it reaches the ground level rolls, sticking to these rolls will also occur. Finally, if the coated web is not completely cooled when it is wound on the take-up roll, the layers will stick to each other and will not be able to be unwound at their point of sale or use.

Various methods have been utilized to attempt to eliminate the tacky condition and to cool the coated web to overcome the aforementioned problems. Conventional coating materials such as asphalt or bituminous compositions have poor heating and cooling characteristics. Cooling of the heated coated web on both surfaces as it travels in the vertical direction between the dip-tank and the driven and idler rollers at the upper position of travel helps reduce the sticking problem somewhat but the sticking still occurs to an unsatisfactory degree. Refrigeration cooling has been attempted but is expensive and slows production to a level where it is not economically possible to operate the process. No appreciably favorable results have been obtained by refrigerating or similarly cooling the driven roll itself at its upper driving position.

It is at this upper position at the superstructure where the greatest elforts and expense have been expended to eliminate the problem of sticking, so that the web may be wound into a finished product.

For example, various water treatment methods have been attempted at this point the process with little success. An open tank placed at the upper position at the end of the vertical run has been filled with water with a metal driven roll immersed in it. While this presents a continuously wetted roll to the coated web, the metal surface of the driven roll does not pick up and transfer sufiicient water to the coated web to eliminate the sticking problem. Another water treatment method attempted has involved the immersion of the coated web in water within an open tank in order to effect cooling and reduce the tacky state of the coating. However, a water pick-up problem with the coated web results which renders this method unsatisfactory. The driven roll and the subsequent idler rolls have also been coated with a non-adherent plastic material, such as Teflon, with no success in eliminating the sticking problem.

Theonly method that has been commercially practicable and which is currently in use involves the appplication of a powder material such as talc and/ or mica to one or both sides of the coated web at the top of the vertical run at the upper superstructure position. However, this method has continuously presented problems both of housekeeping and application. In order for the tale powder to properly adhere to the coated web, fine mesh talc powder must be used. Although various attempts have been made to confine the application of the tale powder to the coated web, housekeeping problems occur, particularly due to the dust formed. Thus dust affects both the machinery and the health of the employees and causes maintenance costs to be high. Attempts to completely enclose the upper superstructure position to make a relatively air-tight chamber were no effective since they resulted in the jamming of the equipment within the chamber. In addition, the talc dust escaped out of the slits through which the coated web was adapted to pass. This greatly reduced the effectiveness of this method.

Further methods of applying the talc powder were attempted such as placing the upper superstructure in a negative exhaust pressure chamber and applying the tale in a slurry state. Both of these additional methods have had similar shortcomings.

In addition to the foregoing, the use of materials such as talc presents secondary problems related to control of the amount of talc used. When too little of the tale powder is used, the layers of the coated web stick together and problems in unrolling the material from the take-up roll result. When too much of the talc powder is used, problems occur in the salability of the product, since the excess powder decreases its attractiveness and presents handling problems.

In addition to those listed above, other attempts to eliminate the foregoing problems have been made by applying various release papers and/or plastic films on both sides of the coated web, such as waX-kraft paper, chemically treated paper, polyethylene films, Mylar films, cellophane films, polyvinylchloride films and so forth. Some of these films have reduced the problems of sticking and facilitated the talc powder application but they have created other difficulties since the release papers or films must be removed from the finished product before it is wound on the wind-up roll. This use of release papers or film is accordingly undesirable since it increases manufacturing costs.

Still further attempts have been made to eliminate the problems involved in the process by spraying the coated web with water on one or both sides during the vertical travel distance between the dip-tank and the upper superstructural position. However, this created a water collection problem since the water tended to run off down the coated web into the dip-tank.

The present invention provides a process for continuously coating an elongated sheet of material with a tack substance wherein the above-mentioned disadvantages are eliminated. This invention broadly involves the cooling and drying of the tacky substance by causing the coated sheet of material to pass over and in contact with an absorbent surface which contains an absorbed fluid which will prevent the coated sheet of material from sticking to the absorbent surface and which, in a preferred embodiment, will cool the tacky substance as it comes in contact with the absorbent surface.

It is accordingly a primary object of the present invention to provide a novel coating process wherein a continuous web coated with a tacky substance is treated to prevent sticking.

It is a further object of the present invention to provide a novel coating process wherein a continuous web coated with a tacky substance is wetted and cooled through contact with a liquid contained in an absorbent surface to eliminate sticking problems.

It is still another important object of the present invention to provide apparatus including a novel absorbent surface which makes possible the wetting and cooling of a tacky coated web to prevent sticking.

These and further objects and advantages of the present invention will become more apparent through reference to the following description and appended claims, as well as to the accompanying drawings wherein:

FIG. 1 is a diagrammatic representation of the coating process of the present invention;

FIG. 2 is an isometric view of the wetting and cooling endless belt apparatus of the invention;

FIG. 3 is a view of an alternate apparatus of the invention; and

FIG. 4 is a view of another alternate apparatus of the invention.

The novel apparatus and method of the present invention may best be described by reference to FIGS. 1 and 2 of the drawings. While the present process is applicable to the coating of any elongated sheet of material with a sticky or tacky substance, whether such substance is a hot melt material or one which is a cool fluid, the invention will be described in connection with a preferred embodiment involving an elongated web or sheet of material coated with a hot-melt asphaltic substance.

An elongated sheet of material to be coated passes from a supply roll 12 over an idler roll 14 into a dip-tank 16 which contains asphalt 17 which is heated to a sufliciently fluid condition by conventional heating means (not shown). Since sheet 10 passes into tank 16 around idler rolls 18 and 20, the sheet will be coated on both sides with the asphalt 17. The amount of coating on the web material 10 is controlled by heat in conjunction with spreader blades (not shown) which are mounted both above the dip-tank 16 and above the level of the asphalt composition within the tank 16 above idler rolls 18 and 20.

As the asphalt coated web 10 leaves the heated dip-tank 16, the temperature of the coating is approximately 275 F. The coated web 10 travels vertically a distance of approximately 15-20 feet where it passes over an endless belt 24 which is carried by a driven roll 22 and idler roll 26. The structure including the novel endless belt 24 will be described hereinbelow in greater detail. The coated web 10 then proceeds downward to ground level to driven rolls 28 and 30, over idler r011 32 and finally is wound on a take-up roll 34.

In roofing materials, waterproofing, fiashings and building product applications, consumers expect their products to be provided with decorative materials such as coarse mica flakes, roofing granules, sand and/or other materials. Where the coated sheets made in accordance with the present invention are destined for such applications, the decorative or like materials are applied to the coated sheet 10 by applicator mechanism 42 which is positioned immediately above driven rolls 28 and 30. When the coated web 10 reaches its lower position at the driven rolls 28 and 30, it is still slightly tacky. This permits the decorative materials to adhere to the surface of the coated web 10. The rate of flow of these materials from applicator mechanism 42 can be controlled by any conventional mechanical or electrical means. Excess decorative materials, which might fall off the coated web 10, can be collected in an open pan 44 which is positioned under the point of application and the collected material may be reused.

As indicated above, details of the novel endless belt structure of the present invention are shown in FIG. 2. An endless belt 24, which is preferably made of a solid woven cotton material which is adapted to absorb and hold water, is mounted on driven roll 22 and idler roll 26. The endless belt 24 is mounted over a tank 36 which is filled with a cooling fluid such as water so that the lower portion of the belt passes through the water and becomes wetted.

Water is introduced into tank 36 by means of a perforated pipe 38 which sprays water on the inner surface of the endless belt 24, as shown, with the excess water not adhering to the underside of the belt 24 falling into the tank 36. Spraying is regulated by a valve (not shown) which controls the fiow of water. The level of water within the tank 36 is regulated by an overflow drain 40 which is positioned near the top of the tank. Endless belt 24 is driven through the tank 36 by the driven roll 22 and as it revolves it picks up water. At the end of the vertical run from the dip-tank 16, the hot and tacky asphalt coated web 10 passes over the wetted endless belt 24. As will be apparent from FIGS. 1 and 2, revolution of the driven roll serves not only to drive the endless belt 24 but to move coated sheet 10 through the coating system.

The endless belt 24 around driven roll 22 and idler roll 26 may be adjusted for tension by adjustable bearings on the arbors of the idler roll 26. Tracking can be controlled by crowning or movement of idler roll 26. Further tensioning controls can be accomplished by the introduction of adjustable idler rolls above or'below the underside of the endless belt in any convenient location between the driven roll 22 and the idler roll 26.

The construction of the mechanism including endless belt 24 makes it ideally suited to eliminate the problems presented by prior art systems. A suflicient amount of water is picked up by the endless belt 24 and brought in contact with the coated sheet 10 to cool and set the coating so as to eliminate sticking problems without the attendent water pick-up problems which occur when the coated sheet is completely immersed in water as has been done in prior art processes. After the coated sheet 10 passes over the endless belt 24 at the idler roll 26, it is still sufiiciently warm to dissipate the small amount of water film which was picked up from the endless belt 24 and remains on the surface of the coated sheet 10. Further drying of this water, if necessary, can be accomplished by suitable radiant heat bulbs or other warm air circulation anywhere in the process during its downward travel. Since the coated web 10 does not stick to the endless belt 24, the problem of the coating sticking on the driven and idler rolls (as in prior art methods) is completely eliminated. As will be appreciated, the vertical distance which the asphalt coated sheet 10 travels from the dip-tank 16 to the driven roll 22 aids in cooling and setting of the asphalt coating. When the novel apparatus in the present coating process is used, the vertical distance from the dip-tank to the driven roll 22 may be reduced substantially without adverse effect, thus permitting a saving in the building height.

As will also be recognized, by increasing the length of endless belt 24, the coated sheet would be in contact with the wetted surface for a longer period and the cooling and setting eifect on the coating would be enhanced correspondingly. Conversely, by decreasing the length of the endless belt, the coated web will not be cooled as much. The endless belt length can be varied to provide the exact degree of cooling desired in a particular application.

As previously indicated, the cooling fluid (water, in the preferred embodiment) is fed into tank 36 by means of a perforated pipe 38. Since this pipe is arranged to spray water on the inner surface of the endless belt 24, this feed arrangement serves the dual purpose of feeding cooling fluid into tank 36 enhancing the cooling effect on the endless belt (and thus ultimately on the tacky coating on sheet 10). While this is accordingly a highly advantageous arrangement, the basic advantages of the novel system of the present invention can still be attained with a conventional cooling fluid feed arrangement in tank 36.

Various modifications of the foregoing system are possible and practical within the spirit of the present invention. For example, as shown in FIG. 3, the endless beltdriven roll-idler roll combination can be completely eliminated by wrapping a length of material 50 similar to the woven cotton belt of the above-described apparatus completely around the peripheral face of a driven roll 52 so that the periphery of this roll is completely covered. This roll is then partly submerged in a water tank 54 (as driven roll 22 was in tank 36) so that material 50 absorbs water as it rotates. By elimination of the idler roll (which is not necessary in the system of FIG. 3), the coated web travels directly to the lower position at which final decorative additions are made and final winding of the coated sheet takes place. This construction would be practical where the sticking and cooling problems are not as great as those described above.

Another variation of the single roll wetting apparatus shown in FIG. 4, eliminates the need of passing the roll through a water tank. In this embodiment, the driven roll 60 is hollow and has a porous peripheral face 62. A water inlet 64 and water outlet 66 are provided in the ends of the roll 60 with roll 60 being mounted in appropriate rotary joints permitting pressurized water ingress and egress as roll 60 rotates. Water or other cooling fluid applied to the interior of the driven roll 60 under pressure is forced through the porous face 62 of the roll 60 and wets the coated web passing over it to wet it, as in the previous embodiments discussed above. The volume and pressure of the water is controllable and variable so more or less water can be presented to the coated web. A drip pan 68 is provided to collect excess water which falls from the porous face 62 of the driven roll 60.

The preferred material for use in fabricating the endless belt 24 (or the corresponding absorbent surfaces used in the embodiments of FIGS. 3 and 4) is a cotton belting, an excellent form of such belting being a 2-ply Easton white solid woven cotton belting (endless net length square lap). Other absorbent materials can be employed, however, to obtain the benefits of the present invention.

Similarly, while the present invention is particularly adapted for treating tacky coatings such as asphaltic or bituminous substances, the novel process and apparatus previously described are adapted for use for a variety of purposes, including the manufacture or processing of butyl products, neoprene, polyvinyl chloride, reinforced or non-reinforced sheets or films and the like, wherever cooling and sticking problems of the nature previously described are encountered.

And while the present invention has been described in connection with hot melt materials, tacky coating substances which are not heated may be similarly employed, in which case any heating means provided in tank 16 will be unnecessary.

A variety of web or sheet materials can be coated in the process and apparatus of the present invention. Exemplary of such materials are metal foils, rag and asbestos felts, paper and plastic films, non-woven and woven cotton cloths, wire meshes, fiber glass cloths, burlap cloths and the like.

In addition to advantages previously discussed, with the novel coating process and apparatus of the present invention, the necessity for applying talc powder to the web is eliminated. This reduces costs and does away with the unhealthy environment and the housekeeping problems caused by talc dust. The process of the present invention also improves the appearance of the product and facilitatis laminating or bonding of other webs onto the coated we s.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment and processes are therefore to be considered in all aspects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed:

1. A method for preparing a continuous web of material which comprises the combination of the steps of: coating said web of material with a tacky substance characterized as generally adhering to both relatively warm and relatively cool surfaces while tacky; setting said substance by causing the coated web to travel over a first path having an upward vertical component to permit said substance to set at least partially and to lose at least a portion of its tackiness; changing the direction of travel of said web from said first path to a second path having a downward vertical component by passing a coated surface of said web of material over and in contact with an absorbent surface capable of absorbing a fluid which prevents the adherence of said partially-set tacky substance to said absorbent surface, said absorbent surface being located inter mediate said first path and said second path; applying said fluid to said absorbent surface to prevent said coated web of material from sticking to said absorbent surface; the method being further characterized in that the coated surface of said web is free from contact with any supporting surface between said coating step and the point of contact of said web with said absorbent surface in said direction-changing step.

2. A method as defined in claim 1 wherein said fluid is at a temperature lower than that of said tacky substance so that said substance will be cooled as the web comes in contact with said absorbent surface.

3. A method as defined in claim 2 additionally comprising the step of spraying an additional amount of said lower temperature fluid on said absorbent surface to further wet said absorbent surface and to enhance the cooling of said material as said material comes in contact References Cited with said absorbent surface. N T D E P T 4. A method as defined in claim 1 wherein said sub- U I E T S ATEN S stance is an asphaltic material. 2 3533 11 5 2 55 WaStLarfX method as defined 1n clalm 4 wherein said fluid 1s 5 2:483:60s 10,1949 Abramson 118-59 6. A method as defined in claim 1 wherein said ab- 3'524'425 8/1970 Barnes et 117158 X ioglgegntasgrgiig is caused to move so as to drive said web WILLIAM D- M ARTIN Primary Examiner s 1 7. A method as defined in claim 1 wherein said ab- 10 LUSIGNANASSIStaDt Examine! sorbent surface is a woven cotton web.

8. The method as set forth in claim 1 wherein said absorbent surface assists in driving said web through the 125 Q 1Z6 Q, 1 coating system. 11869 

